AC Charging R134a Astro 1997

I have the 1997 Chevy Astro and I cannot find the low-service port to charge it up. It has not been charged in 7 years. Anyway I noticed a port on the accumulator that the bottle fits on it however that is not the correct port. There is metal line next to my radiator cap and the bottle does not fit on that port. I just can’t seam to find it. Is it under the car somewhere or in the engine cover?

Thanks
Eric

Not an expert with it but I charged it through that top valve and it worked.

The low side is the port at the accumulator. Remember, R134A uses a different connection than R12, so make sure the hose you a connecting to it is for R134A. ( R134A has a collar that pulls back, and after it is attached, pushes forward to lock on the adapter. R12 is a threaded adapter.)